A student investigates how the thickness of felt insulation affects the cooling of hot water in a glass beaker.
She wraps different thicknesses of felt around a beaker containing 150 cm3150\text{ cm}^3150 cm3 of hot water. At the start of each test, she records the initial temperature of the water, and then records the final temperature after 15 minutes.
The table below shows her results:
| Thickness of felt (mm) | Start temperature (°C) | End temperature after 15 mins (°C) | Temperature difference (°C) |
|---|---|---|---|
| 1 | 85 | 55 | 30 |
| 2 | 87 | 61 | 26 |
| 3 | 86 | 64 | 22 |
| 4 | 84 | 66 | 18 |
| 5 | 88 | 74 | 14 |
| 6 | 85 | 45 |
Calculate the temperature difference when the thickness of the felt is 6 mm6\text{ mm}6 mm.
The result when the thickness of the felt is 6 mm6\text{ mm}6 mm is anomalous. Suggest a reason why this result appears to be anomalous, referring to the trend shown by the other results.
Describe how the rate of cooling of the water is affected as the thickness of the felt insulation increases.
47 exam-style questions on OCR GCSE Physics Practical skills. Each one has a worked solution and a mark scheme showing where the marks go.